This invention in general relates to an improved conveyor and pallet structure in which the pallet supports greater weights than in the prior art. In addition, the improved conveyor allows the pallet to be easily removed from the conveyor for placement on a second conveyor, or repair of the pallet.
A known type of conveyor employs chains to frictionally engage and move a part carrying pallet through a conveyor distance. Modern chain conveyors typically include two shafts rotating about parallel axes that are spaced from each other by a conveyor distance over which pallets are to be conveyed. In a common type of chain conveyor, each of these shafts have two sprocket sets, each having two separate sprocket gears spaced axially along the shaft. Endless three-link chains are mounted upon one sprocket set on each of the shafts and extend along the conveyor throughout the conveyor distance. The endless chains are thus also spaced by an axial distance corresponding to the distance between the sprocket sets. Pallets are mounted in contact with the endless chains and are driven along the conveyor distance by frictional contact with the three-link chains. The pallets will typically travel along the upper extent of the chain, commonly known as an upper run, reach the end of the conveyor distance, are pivoted beneath the sprocket sets, and travel on the endless chain below the sprockets, commonly known as the lower run.
In many prior art chain conveyors, the chains may be supported upon the chain links closest to the axial ends of the conveyor, and the third chain link, which is the axially innermost chain link, supports the pallet. Since the three-link chain in the conveyors must bear the weight of the pallet from an innermost ;link, and is cantilever supported at an outer link, a moment arm is created about the outermost link of the chain that may result in the chain binding or bending if an overly great weight is placed upon the pallet.
In the past, the chains were often covered at vertically upper positions by supports, which prevented access to the chains. Also, any debris or chips could become lodged between the supports and the chain.
In addition, the prior art pallet had frictional contact members that contact the chain during the upper and lower runs, such that there was insufficient clearance between the contact members and the chain to allow the pallet to be easily removed from the chain conveyor system. In many of the prior art chain conveyors, the pallet needed to be disassembled in order to be removed from the endless chains.